Abstract
A 79-year-old woman presented with a long history of peripheral eosinophilia. Previous right hemicolectomy for colonic polyposis was reported. Laboratory tests were notable for mild macrocitic anaemia and eosinophilia. β2 microglobulin and serum tryptase levels were elevated. Serum immunofixation revealed IgA/kappa monoclonal protein. Bence-Jones protein was positive. Bone marrow (BM) biopsy revealed the coexistence of two neoplastic components. Cohesive clusters of bland-looking, spindle-shaped mast cells, representing 20% of marrow cellularity, were close to aggregates of mature plasma cells occupying 40% of marrow cellularity. Molecular analysis on marrow aspirate demonstrated KIT D816V mutation, TET2 mutation, monoallelic deletion of TP53/17p13 and trisomy of ATM/11q23. A bone density study revealed mild osteoporosis. Full skeletal X-rays and magnetic resonance imaging (MRI) of spine and hips showed multiple, small rarefaction areas and an old L1-L2 fracture, both ascribed to osteoporosis. The association of systemic mastocytosis (SM) and multiple myeloma (MM) is very uncommon. The coexistence of SM with MM placed our patient in the SM with associated clonal haematological non-mast-cell lineage disease (SM-AHN) subtype. Midostaurin therapy was started.
Highlights
Bone marrow aspirate confirmed the presence of the two neoplastic components (Figure 5)
The diagnosis of systemic mastocytosis (SM) was proposed owing to the fulfilment of the major diagnostic criteria and three of the minor criteria (KIT D816V mutation, CD25 expression, serum tryptase level exceeding 20 ng/mL) combined with the presence of a C finding [1]
Due to the bone marrow findings, along with the absence of myeloma-defining events, our patient fitted into the diagnosis of smoldering MM
Summary
Serum tryptase (138 ng/L; reference range 0–11.4) were elevated. Bone marrow (BM) biopsy revealed two neoplastic components. Low- and high-power views of haematoxylin and eosin sections showed cohesive paratrabecular aggregates of bland-looking, spindle-shaped cells (Figure 1; Figure 2 lower part) positive for CD117 (Figure 3), tryptase and CD25 representing 20% of marrow cellularity. Aggregates of mature plasma cells (Figure 1; Figure 2 upper part) positive for CD138 (Figure 4), MUM1/IRF4 and kappa light chain occupied 40% of the remaining bone marrow.
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